Preheat your oven to 150°C (300°F). Pat the Bone-In Lamb Shoulder dry and rub generously with Salt and freshly ground Black Pepper, then sprinkle with Dried Thyme and tuck a few Bay Leaves around the meat.
Heat a large heavy ovenproof pot with a splash of Neutral Oil over medium-high heat. Sear the lamb on all sides until well browned, then add about 2 cups of Water to the pot (enough to come partway up the shoulder), cover tightly and transfer to the oven. Roast low and slow for 3–4 hours, or until the meat is easily pulled apart with a fork.
While the lamb cooks, prepare the pilaf. Rinse the Long-Grain Rice until the water runs clear and drain. In a saucepan, melt the Butter with a little Olive Oil, add the Orzo and toast until golden, then stir in the drained rice.
Pour in hot Chicken Stock (use about 1.5 times the volume of rice), season lightly with Salt, bring to a simmer, cover and cook on low until the rice is tender and the liquid absorbed, about 15–18 minutes. Fluff with a fork and keep warm.
Make the sumac onion: thinly slice the Red Onion and toss with Ground Sumac, a pinch of Salt, a squeeze of Lemon Juice and a drizzle of Olive Oil. Add chopped Parsley and set aside to mellow.
Char the vegetables: toss the Turkish Green Peppers and halved Tomatoes with a little Olive Oil and Salt, then roast in the oven (or grill) until blistered and slightly collapsed, about 15–20 minutes.
When the lamb is done, remove it from the pot and let it rest briefly. Reserve some of the braising juices, then shred the lamb with forks, discarding large bones and any excessive fat. Toss shredded meat with a few spoonfuls of the strained juices to keep it moist.
Warm the Lavaş briefly in the oven or on a dry skillet. To serve, layer warm lavaş with a spoonful of pilaf, a generous mound of shredded tandır lamb, charred peppers and tomatoes, and finish with the sumac-onion and a drizzle of the reserved braising juices or more Olive Oil.
